Generalize link_dm_node() it works for all devices

Also accept some new parameters to adjust offsets and startsecotrs when creating the disk mapping

base/fs/volume.py

@@ -11,12 +11,15 @@ class Volume(FSMProxy):
 
 	events = [{'name': 'create', 'src': 'nonexistent', 'dst': 'detached'},
 	          {'name': 'attach', 'src': 'detached', 'dst': 'attached'},
+	          {'name': 'link_dm_node', 'src': 'attached', 'dst': 'linked'},
+	          {'name': 'unlink_dm_node', 'src': 'linked', 'dst': 'attached'},
 	          {'name': 'detach', 'src': 'attached', 'dst': 'detached'},
 	          {'name': 'delete', 'src': 'detached', 'dst': 'deleted'},
 	          ]
 
 	def __init__(self, partition_map):
 		self.device_path = None
+		self.real_device_path = None
 		self.partition_map = partition_map
 		self.size = self.partition_map.get_total_size()
 
@@ -25,6 +28,8 @@ class Volume(FSMProxy):
 			def set_dev_path(e):
 				self.partition_map.root.device_path = self.device_path
 			callbacks['onafterattach'] = set_dev_path
+			callbacks['onlink_dm_node'] = set_dev_path
+			callbacks['onunlink_dm_node'] = set_dev_path
 
 		cfg = {'initial': 'nonexistent', 'events': self.events, 'callbacks': callbacks}
 		super(Volume, self).__init__(cfg)
@@ -36,3 +41,47 @@ class Volume(FSMProxy):
 	def _check_blocking(self, e):
 		if self.partition_map.is_blocking():
 			raise VolumeError('The partitionmap prevents the detach procedure')
+
+	def _before_link_dm_node(self, e):
+		import os.path
+		from common.fs import get_partitions
+		proc_partitions = get_partitions()
+		device_name = os.path.basename(self.device_path)
+		device_partition = proc_partitions[device_name]
+
+		# The sector the volume should start at in the new volume
+		logical_start_sector = getattr(e, 'logical_start_sector', 0)
+
+		# The offset at which the volume should begin to be mapped in the new volume
+		start_sector = getattr(e, 'start_sector', 0)
+
+		sectors = getattr(e, 'sectors', self.size * 1024 * 1024 / 512 - start_sector)
+
+		table = ('{log_start_sec} {sectors} linear {major}:{minor} {start_sec}'
+		         .format(log_start_sec=logical_start_sector,
+		                 sectors=sectors,
+		                 major=device_partition['major'],
+		                 minor=device_partition['minor'],
+		                 start_sec=start_sector))
+		import string
+		import os.path
+		for letter in string.ascii_lowercase:
+			dev_name = 'vd' + letter
+			dev_path = os.path.join('/dev/mapper', dev_name)
+			if not os.path.exists(dev_path):
+				self.dm_node_name = dev_name
+				self.dm_node_path = dev_path
+				break
+
+		if not hasattr(self, 'dm_node_name'):
+			raise VolumeError('Unable to find a free block device path for mounting the bootstrap volume')
+
+		log_check_call(['/sbin/dmsetup', 'create', self.dm_node_name], table)
+		self.unlinked_device_path = self.device_path
+		self.device_path = self.dm_node_path
+
+	def _before_unlink_dm_node(self, e):
+		log_check_call(['/sbin/dmsetup', 'remove', self.dm_node_name])
+		del self.dm_node_name
+		del self.dm_node_path
+		self.device_path = self.unlinked_device_path

common/fs/loopbackvolume.py

@@ -1,18 +1,9 @@
 from base.fs.volume import Volume
 from common.tools import log_check_call
-from base.fs.exceptions import VolumeError
 
 
 class LoopbackVolume(Volume):
 
-	events = [{'name': 'create', 'src': 'nonexistent', 'dst': 'detached'},
-	          {'name': 'attach', 'src': 'detached', 'dst': 'attached'},
-	          {'name': 'link_dm_node', 'src': 'attached', 'dst': 'linked'},
-            {'name': 'unlink_dm_node', 'src': 'linked', 'dst': 'attached'},
-	          {'name': 'detach', 'src': 'attached', 'dst': 'detached'},
-	          {'name': 'delete', 'src': 'detached', 'dst': 'deleted'},
-	          ]
-
 	extension = 'raw'
 
 	def create(self, image_path):
@@ -26,42 +17,6 @@ class LoopbackVolume(Volume):
 		[self.loop_device_path] = log_check_call(['/sbin/losetup', '--show', '--find', self.image_path])
 		self.device_path = self.loop_device_path
 
-	def _before_link_dm_node(self, e):
-		import os.path
-		from . import get_partitions
-		proc_partitions = get_partitions()
-		loop_device_name = os.path.basename(self.loop_device_path)
-		loop_device_partition = proc_partitions[loop_device_name]
-
-		sectors = self.size * 1024 * 1024 / 512
-		table = ('{log_start_sec} {sectors} linear {major}:{minor} {start_sec}'
-		         .format(log_start_sec=0,
-		                 sectors=sectors,
-		                 major=loop_device_partition['major'],
-		                 minor=loop_device_partition['minor'],
-		                 start_sec=0))
-		import string
-		import os.path
-		for letter in string.ascii_lowercase:
-			dev_name = 'vd' + letter
-			dev_path = os.path.join('/dev/mapper', dev_name)
-			if not os.path.exists(dev_path):
-				self.dm_node_name = dev_name
-				self.dm_node_path = dev_path
-				break
-
-		if not hasattr(self, 'dm_node_name'):
-			raise VolumeError('Unable to find a free block device path for mounting the bootstrap volume')
-
-		log_check_call(['/sbin/dmsetup', 'create', self.dm_node_name], table)
-		self.device_path = self.dm_node_path
-
-	def _before_unlink_dm_node(self, e):
-		log_check_call(['/sbin/dmsetup', 'remove', self.dm_node_name])
-		del self.dm_node_name
-		del self.dm_node_path
-		self.device_path = self.loop_device_path
-
 	def _before_detach(self, e):
 		log_check_call(['/sbin/losetup', '--detach', self.loop_device_path])
 		del self.loop_device_path